Finding the needle in the haystack

Story

04 May 2017

When radar was first introduced during the Second World War it typically looked at the middle range, before evolving to have a detection range that fitted the time needed to reach the target, whether that was scrambling fighter jets or guiding missiles.

Further development led to radar becoming smaller while covering larger areas. This was very successful until opponents began creating problems, one of which was stealth.

“A lot people believe stealth means invisible,” says Anders Linder, head of Surface Radar Solutions at Saab. “But there is only one invisible product in the world: Harry Potter’s invisibility cloak.”

Stealth is actually the ability to become smaller in the eyes of radar, so that if you look at it from different angles you will see it differently.

“Take a missile that is seven meters wide and one meter in dimension,” says Anders Linder. “That is a big missile by any measure but if you look at it from different angles it has different sizes.

If we look at the missile from one angle it’s the size of a basketball. From another, tougher angle it’s the size of a basketball, and from the toughest angle, this huge missile is the size of a golf ball. Now imagine trying to find a golf ball travelling at a high speed for a long distance. It’s not easy.

“The detection range of existing radar is much shorter than the distance needed for interception,” explains Anders Linder. “And the arms race of today is a battle between stealthier targets and increasingly advanced radar."

Another problem is drones, or unmanned aerial vehicles (UAVs). They’re not stealthy but they are small and they fly low and slow. The problem is not seeing them, it’s that there are other small things flying low and slow: birds.

Imagine a radar operator seeing one hundred targets on the screen and 99 of them are birds. That’s a lot of clutter. Increasing the ‘brains’ of the radar allows it to separate out birds and the operator no longer sees them.

A third problem is jamming. If you have good radar, opponents will try to jam it by throwing a lot of energy and microwaves against it. In order to detect the target the radar needs to be sharp enough to send a very thin, powerful signal through the middle of the jamming. This is comparable to trying to hear a bumblebee while standing on a runway while a plane takes off. It sounds impossible but it’s the equivalent of what modern radar is capable of doing.

Anders Linder says, “Modern radar is capable of addressing three big problems: stealth, birds, and a jammed environment – and it will continue to evolve as opponents and other factors create new problems.”